Thanks. So it's effectively back to good old "stop-down metering". At any rate, it's nice that you can get the LV histogram to work right on these two cams. At the same time, I am surprised a) at the fact that you can't get it to work right on earlier Panys and b) that you have to enter "constant preview" to get it to work right on the GH2 and GH3. There is no good reason, as far as I can see, why they couldn't make it work right even with the physical aperture kept wide open. Unlike the old cams that were forced to rely on "stop-down metering", a modern cam has all the information it needs to get it right anyway.

I was mistaken in saying that constant preview has to be on (I always have it on). The histogram also slides back and forth according to exposure compensation changes in the auto modes.

Thanks for the update. Good to know for the future.

It "slides back and forth", but remains so unchanged in the appearance of the histogram display pattern itself (in all but "Constant Preview" mode) that it appears to be the very same data simply amplified or attenuated (which amounts to a lateral shift along the X-axis where the logarithmic scale is rather close to approximately 20% of full-scale per EV to around -4 EV down below full-scale).

In any case, I don't find it all that useful. I'm thinking now that the best way to meter the GH3 for RAW is to let the camera figure the proper exposure and then dial in 2/3 - 1 stop of positive exposure compensation. Needs much more testing, though, and of course that assumes that the shutter speed is sufficient at one's preferred aperture setting.

Why don't you find it useful? With digital (unlike film), it makes good sense to me to pay primary attention to the highlights rather than medium gray.

It is useful if one wants to have faith that the display is derived using the actual F-Number ...